Method for manufacturing impulse cams for dials



Jan. 19, 1960 c. o. SOHLBERG 2,921,482

METHOD FOR MANUFACTURING IMPULSE CAMS FOR DIALS Filed May 16. 1957 Fig. 1 Fi 2 IN VENTOR CHRL 05cm J'a/u. azea METHOD FOR MANUFACTURING IMPULSE CAMS FOR DIALS Carl Oscar Sohlberg, Stockholm, Sweden, assignor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Application May 16, 1957, Serial No. 659,555

Claims priority, application Sweden June 20, 1956 Claims. (Cl. 74-567) The present invention relates to such an impulse cam for a dial, which after the winding up of the dial at its returning movement operates an impulse contact according to the taken digit. On the one side of such an impulse cam there is a stop spring and on the other side a carrier spring. The stop spring prevents the backwards turning of the impulse cam at the winding up of the dial and the carrier spring is arranged to connect the impulse cam with a rotating carrier wheel at the returning of the dial. These two springs are usually riveted to the impulse cam. The purpose with the present invention is to avoid the time-consuming fastening procedure hereby arisen. According to the invention this is obtained thereby that the two springs are manufactured from a spring band connected together in one piece, which between the springs is so bent that the springs will lie almost parallel, whereafter the springs are pushed in over the impulse disc so that they snap over an elevation on this.

The invention is to be further described with reference to the attached drawing showing an example of the application of the invention. Fig. 1 shows the two springs manufactured in one piece, Fig. 2 shows from the side the two springs after being bent. Fig. 3 shows United States Patent 0 the impulse cam. Figs. 4 and 5 are different sections not shown parts can be of normal nature. At the manufacturing of the impulse cam with belonging springs it is proceeded according to the invention in the following way.

The spring piece 1 shown in Fig. l is punched out from a spring band, said piece band 1 consists partly of the stop spring 2 and the carrier spring 3 and partly of two fixing slots or hole rings 10. This spring piece is thereafter bent at its middle part in two places on: 90 or a little more, so that seen from the side it get that in Fig. 2 shown shape. At the same time the two springs 2 and 3, which after the bending lie almost parallel, are flexed out a little from each other. An impulse cam has three impulse cams 8 and between them apertures 7 as appears in Fig. 3. At the manufacturing of the impulse cam from an insulating piece the one aperture is equipped with two slots 5 and 6, and the nave 9 in the middle of the cam is made a little raised. At the fastening of the spring piece 1 to the impulse cam it is pushed in either in the slot 5 or in the slot 6 depending on if an impulse cam 8 is to hold the contact between the impulse springs 11 of the dial closed or broken in the initial position of the dial. At the mounting on the spring piece 1 is pushed in so far. that the two holding rings 10 lying opposite each other will snap over the nave 9 on both sides of the impulse cam. The

impulse cam with mounted on springs obtains therewith the shape shown in Figs. 4 and S.

If the spring piece 1 is pushed in over the slot 6, the impulse cam will after being mounted on its place in the dial in its initial position like that in the Fig. 6 shown position in relation to the two impulse springs 11 consisting of two parallel, with a certain tension against each other lying springs. When the stop spring 2 is barred by a slot 12 in the body of the dial 13 the tips of the contact springs 11 will always be lying in one of the apertures 7 between two impulse cams 8. Then when the impulse cam is brought into rotation, the contact between the two impulse springs 11 is broken in theusual way each time a cam 8 passes between them. If the spring piece 1 is mounted in the other slot 5, Fig. 7, a cam 8 will always be lying between the two impulse springs 11 at the initial position of the dial, said cam holding the springs separated. When the impulse cam rotates, there will be contact closing between the two springs each time an aperture 7 passes.

I claim:

1. A pulse cam drive and stop assembly for use in conjunction with the dial of a telephone hand set, said assembly comprising a substantially fiat rotatable cam disc, a U-shaped springy strip straddling said disc and having side branches substantially parallel thereto, the end portion of each side branch being curved away from the respective disc face, one of said curved end portions constituting a cam stop and the other a cam driver, and interlocking retaining means on the disc and the strip holding the strip in said straddling position.

2. A pulse cam drive and stop assembly for use in conjunction with the dial of a telephone hand set, said assembly comprising a substantially flat rotatable cam disc and a U-shaped springy strip straddling said disc and having side branches extending substantially parallel thereto, the end portion of each side branch being curved away from the respective disc face, one of said curved end portions constituting a cam stop and the other a cam driver, said cam disc having a protrusion on at least one of its faces and the strip branch facing the respective disc face having an aperture receiving said' protrusion to hold the strip in said straddling position.

3. An assembly according to claim 2 wherein said protrusion comprises a raised center hub, said apertured strip branch receiving said hub.

4. A pulse cam drive and stop assembly for use in conjunction with the dial of a telephone hand set, said assembly comprising a substantially flat rotatable cam disc having several circumferentially spaced and radially protruding camming surfaces, a U-shaped springy strip having branches straddling said disc and the bight of the strip engaging the spacing between two of said camming surfaces, the end portion of each strip branch being curved away from the respective disc face, one of said curved end portions constituting a cam stop and the other a cam driver, and interlocking retaining means on the disc and the strip holding the strip in said straddling position.

5. A pulse cam drive and stop assembly for use in conjunction with the dial of a telephone hand set, said assembly comprising a substantially fiat rotatable cam disc having several circumferentially spaced and radially protruding camming surfaces and two circumferentially spaced peripheral recesses between two of said camming surfaces, a U-shaped springy strip having branches of the strip straddling said disc and the bight engaging a selected one of said recesses to vary the location of said curved end portions relative to the camming surfaces, the end portion of each strip branch being curved away from the respective disc face, one of said curved end portions constituting a cam stop and the other a cam driver,

, 3 T and interlocking retaining means on the disc and the "holding the ship "in said straddling position.

References Cited in the file of this patent UNITED STATES PATENTS I 5 662,344 Boyd Nov. 20, 1900 1,105,590 Abbot July 28, 19:14

FOREIGN PATENTS Italy Ian. 17, 1949 

